It is known to use various viewing means for both direct and remote viewing of the interior of vessels such as high pressure vessels and reaction vessels. In several embodiments the easiest way to view the interior of a vessel is to place a viewing port on a side of the vessel. Many of these viewing ports are adapted to receive connecting units which can be attached to the port and provide a direct view into the vessel's interior. Other units that can be connected provide a safety glass viewing window more structurally sound especially for use on the walls of high pressure vessels. Such a viewing window is disclosed in U.S. Pat. No. 4,809,862 issued to Thomas M. Canty. Other earlier U.S. patents disclosing viewing window units of various constructions are U.S. Pat. Nos. 2,744,487; 3,299,851; 3,837,226 and 4,245,566.
In addition to providing better interior lighting and safer viewing units, remote viewing means have been introduced to the industry. It had been recognized that it is very desirable to provide a system for viewing the interior of vessels at remote locations by the use of viewing cameras that not only provide instant viewing but can also allow recording of data at a safe location away from the vessel. This recorded data can be later used with appropriate means to analyze the activity that took place in the vessel. Viewing cameras that afforded this type of viewing and recording are the type disclosed and claimed in U.S. Pat. No. 4,977,418 also issued to Thomas M. Canty.
A serious problem that was recognized was that the camera unit used often would be internally directed to areas of poor lighting. Lighting units were then introduced into these systems which utilized a different port or a portion of the same port within the vessel wall. However, existing process vessels in many instances had only one access port available for camera or other installations such as lighting. The dimensions of a camera and light units required an 8-inch port to accommodate both at the same location. However, unfortunately, most ports or nozzles are not that large. The heretofore used systems often resulted in situations where the light did not adequately illuminate the camera's viewing area to its maximum extent. This was because each viewing and lighting unit was mounted through a different port and was directed differently.
Prior art devices did not adequately solve these below-noted problems:
(A) Sightglasses--Other glass windows provide unsafe viewing and no illumination. There are in existence glass viewports with lights mounted over half the window but they do not provide effective lighting and hinder view due to reflection off the glass surfaces into the viewer's eye. Furthermore, dirt can build up reducing illumination and view and heat of the light can act in a detrimental way upon the glass by creating uneven thermal stresses or detempering tempered glass. By mounting a light in this manner, half of the viewing area of the window is lost.
(B) Camera/Sightglass--Mounting a camera over a sightglass next to a light created the same problems as in (A) above but to a greater extent due to the fact that a typical camera (CCD or tube type) does not pick up an image as well as the human eye. Consequently, it is necessary to introduce more light into the vessel but this causes washout in the camera due to reflection off the window surfaces. If window size is large enough to avoid substantial reflection into the lens, the window diameter limits the process pressures to which such a system can be applied. Further limitations of all-glass windows are described in J. M. Canty U.S. Pat. No. 4,809,862. Limitations of prior art viewing windows and prior art cameras are described as follows in J. M. Canty U.S. Pat. No. 4,977,418.
A serious drawback to the use of these viewing windows is the possibility of failure or rupturing of these windows when used in a high pressure or high temperature system. Personnel using or in the vicinity of these windows could be be seriously inujured if the windows fail to withstand the internal pressure generated within the reaction vessel. Also, electrical equipment in a light or camera could cause an explosion if the viewport failed or blew out. To correct this drawback, a safety glass viewing window was provided in U.S. Pat. No. 4,809,862 (Canty). Canty provided a novel safety viewing window that was substantially safer and more structurally sound for use in a high pressure-high temperature vessel.
To extend the safety of these type devices a viewing of the interior of high pressure process vessels through a remote location at a safe distance from the vessel is highly desirable. There are situations where explosion potential exists during the use of these vessels and optimum safety can be afforded by removing personnel from the area of the vessel location. At the same time window viewing of the interior activity of a reaction (or other) vessel can only provide instant viewing information. For example, if it was desired to play back a foaming operation or reaction process to determine color changes, reaction levels or densities or other relevant factors, instant viewing through a window would not provide such an opportunity. It is highly desirable to provide a system for viewing the interior of such vessels at a remote location by the use of a viewing camera that can not only provide instant viewing but can also allow recording of data for later study or by the use of appropriate computer programs and digital information fully analyze the activity taking place or that earlier took place. A camera viewing could afford substantial advantages in addition to safety than are presently provided by viewing windows for direct personal viewing. There have been some attempts in both (A) standard viewing and (B) hazardous area viewing to utilize cameras for this purpose.
(A) In standard viewing in a high pressure/high temperature system, users have been limited to makeshift methods. Generally, to view the interior of a vessel at a remote location, the user would have to mount a camera onto an existing sightglass window. Any suitable camera may be used. They would then encounter some or all of the following problems that would render the system ineffective:
1. The sightglass and lens if not housed properly would become dirty due to dirt external to the vessel thereby limiting the view.
2. The process fluid or vapors would leak out or flow out due to a sightglass breaking or leaking. This would then destroy the electronics making the system inoperative. Breakage of the glass viewport could expose the electronics and allow problems to develop.
3. Reflection from room lighting would cause the vessel view to disappear if not provided with proper housing. While some systems rely upon purged air, Applicant's particularly designed system does not require this.
(B) Hazardous area viewing to date in industry has been performed by using a nitrogen-purged housing. The nitrogen purge is provided to eliminate and dilute hazardous vapors and prevent them from exploding. The nitrogen-purged housing is made of thin gauge metal with a window that the CCD Camera sees through. The limiting factors in the design are:
1. Purging is a continuous cost of operation.
2. Instrumenting the purge gas and piping the purge gas is very expensive and limits the locations where the camera can be mounted.
3. The gasketed window that the CCD Camera looks through is fragile and subject to breakage. Not only is there maintenance and replacement cost but there is also a major safety hazard created if the purge controls do not operate properly.
4. Hazardous area viewing of a high pressure area has not been attempted due to the combination of problems from 1, 2 and 3 above. One would currently have to use a purge camera housing on a sightglass and suffer from all of the problems mentioned above.
The structures of a camera device on a reaction vessel could easily become corroded and could fail. Uneven glass loading due to uneven bolt or gasket stresses can cause cracking and leakage. Also, corrosive chemicals during extended usage could cause failure of these mounting structures or failure of the camera being used. The camera systems of the prior art are cumbersome, oversized and in many instances tend to reflect light and cause image distortion. In addition, focusing and manipulating of the camera to provide optimum usage has been difficult when using prior art devices. Therefore, while some degree of improvement is provided by camera viewing heretofore used, none of these systems provide an adequate system for reliable and extended usage.
Thus, there is a pressing need for reliable and safe viewing units that provide optimum lighting and remote viewing wherein the camera and lighting means are directed internally from the same port and same unit.